Make <summary> unselectable by default

[xfq]

When expanding/collapsing the <details> element, it's really easy to select the text in the <summary> element accidentally when expanding and collapsing a section quickly (just for a quick short look at the section, for example), which is annoying.

Personally, I'd like to see the selection of the <summary> element disabled by default, but I'm also glad to hear other people's comments on this suggestion.

Bugs in browsers:

• Firefox
• Chromium

[xfq]

There are also some discussions in w3c/i18n-drafts#123.

[annevk]

I don't think we use user-select (defined at https://drafts.csswg.org/css-ui-4/#content-selection) currently for anything and I'm not quite convinced we should start. Unless there's evidence this is a widespread problem this seems like a problem easily addressed by a browser extension.

[domenic]

I think this might be in the realm of browser UX, not spec. E.g. a browser could require dragging further than normal to start a selection from inside a summary element. The actual process of mouse down/move/up translation to selection is the problem here, not selection itself. (For example, we should not prevent keyboard selection or "Select all" or dragging to select everything in a large swathe of the page which contains a single details/summary.) And that translation process is a browser UX design issue, not a spec issue.

[fantasai]

@xfq In w3c/i18n-drafts#123 you noted that links don't have this problem. What's different about links vs summary that makes one a problem and the other not? And could that difference be implemented in UAs, instead of making them unselectable?

(Fwiw I agree with @domenic and @annevk that disabling selection isn't the right solution here, improving browser UX is.)

[tophf]

The unwanted selection appears because of the short interval between the two clicks, which is treated by the browser as a double-click, not because the cursor moves. Indeed this looks like a bug/omission in browsers for not accounting for this scenario.